Process for packaging plastic materials like hot melt adhesives

ABSTRACT

A method for packaging plastic material using a film to surround the material, and more particularly to a method for packaging hot melt adhesives, the resulting package formed thereby, and the film composition used therein. The method is preferably a coextrusion process for packaging a pressure sensitive hot melt adhesive by extruding a hot melt adhesive through a die orifice, and coextruding a wax-based polymeric film to surround the hot melt adhesive. The coated adhesive may then be formed into individual packaged units having a finite size and shape. The polymeric film comprises a composition having at least 25% by weight of a wax material, an enthalpy of fusion of at least about 100 J/g, and an elongation value at break of at least about 100%. Any type of hot melt adhesive formulation can be packaged or surrounded by the polymeric film in the process. Also, the specific enthalpy of fusion desired and/or elongation value at break desired for the polymeric film can be obtained by blending an appropriate amount of partially crystalline ethylene-based polymer together with a thermoplastic elastomeric block copolymer and/or an ethylene based or propylene-based elastomer.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/976,943 filed Oct. 29, 2004 now U.S. Pat. No. 7,328,547.

BACKGROUND OF THE INVENTION

The present invention relates to a method for packaging plastic materialhaving a finite size and shape using a film to surround the material,and more particularly to a method for packaging hot melt adhesives usinga coextrusion process, the resulting package formed thereby, and thefilm composition used therein.

Hot melt adhesives are substantially solid at room temperature, but areapplied in a molten or flowable state. Typically, hot melt adhesives aresupplied in the form of solid blocks, pillows or pellets. However, sincehot melt pressure sensitive adhesives (HMPSA) or other plastic materialsare typically sticky and/or soft at room temperature, there are problemsassociated with handling and packaging of HMPSA. Regardless of the formin which it is provided, a HMPSA not only sticks or adheres to hands,mechanical handling devices and to itself, but it also picks up dirt andother contaminates. In addition, the individual pieces of IIMPSA and/orother low softening point plastic materials will tend to flow or blocktogether into a single solid mass rendering such materials difficult tobe handled and/or packaged. As a result, containment during shipmentand/or storage periods is a critical aspect of delivering HMPSA, othersoft adhesives, or any kind of plastic materials such as sticky and/orsoft polymers.

To address this troublesome difficulty, those skilled in the art haveturned to packaging techniques such as, for example, shipping adhesivecompositions in rigid containers, such as 55 gallon drums, or siliconecoated, corrugated or particleboard boxes, or alternatively, siliconecoated polymer-based trays which are typically manufactured from a highdensity polyethylene. While these solutions will solve the problem,noted above, in some industrial environments, and applications, itpresents a multiplicity of additional difficulties, and other drawbackswhich have detracted from their usefulness. For example, the moretraditional methods of shipping hot melt adhesive compositions createproblems related to the cost and disposal of the packaging materials. Inthis regard, the silicone coated polymer based trays employed forshipping some types of hot melt adhesive compositions are relativelyexpensive to purchase, and the presence of a silicone coating makes sucha container very difficult if not impossible to recycle. Therefore,these trays, or other similar containers, in many instances, are merelycollected and disposed of in landfill sites, thereby creating atroublesome source of pollution. Further, these silicone coatedcontainers create other difficulties in that under certain environmentalcircumstances a great deal of physical force must be applied to theadhesive to extract it from these containers, making the adhesivedifficult and inconvenient to handle.

In response to the shortcomings noted above, some manufacturers haveattempted to produce synthetic trays which are readily recyclable, orwhich can, alternatively, be returned and reused for subsequentshipments of adhesives. Recyclable containers, although attractive bytheir relative simplicity, have not been embraced widely in the industrydue to an obvious lack of commercial appeal. More particularly, thedevelopment of a new, more readily recyclable tray has produced, as abyproduct, retooling, and other manufacturing expenses, which have beensubstantial in some respects, and which have worked as a deterrent tothe adoption of this solution as an answer to the aforementionedshortcomings. Further, reusable containers are generally manufacturedfrom a thicker gauge material to lend a measure of durability to thecontainers such that they may survive multiple uses. As a result, theper unit cost of such containers is usually significantly greater thandisposable containers. Additionally, the costs attendant to collectionand returning the spent containers or trays to the manufacturers forsubsequent use has further caused this proposed solution to be quiteexpensive and therefore commercially unacceptable.

Many other different approaches have been tried to package plasticmaterials like HMPSA. One approach is to use a package material that ismeltable together with and blendable into the molten adhesivecomposition itself just prior to application.

In one such method, molten adhesive is fed directly into a film formedin the shape of a tube, and then individual packaged adhesive units areformed by squeezing, sealing and cutting the tube. Such a process issometimes referred to as a “form, fill and seal” process. For example,U.S. Pat. No. 5,373,682 describes a method where molten adhesive ispumped into a cylindrically-shaped tube of plastic film while theexterior surface of the film is sprayed with cooling water. Theresultant individual packages referred to as “cartridges” are allowed tocool until the adhesive solidifies. Another example of making cartridgesof this type is illustrated in U.S. Pat. No. 5,392,592.

In U.S. Pat. No. 6,430,898, low complex viscosity film materials areused to surround a hot melt adhesive. The film material is composed ofan ethylene/α-olefin interpolymer, which is a metallocene or single-sitecatalyzed interpolymer of ethylene and at least one C₃-C_(20α)-olefin.

Rouyer et al, in U.S. Pat. No. 5,527,491, and U.S. Reissue Patent 36,177approaches the problem of shipping cold flowing, pressure sensitive hotmelt adhesive compositions by designing a package which encloses thepressure sensitive adhesive and is meltable along with the adhesive. Inthis instance, the package is a polymer based film which will melt whenexposed to the heat of application machinery.

In PCT applications WO 02/061009 and WO 04/037671, it is claimed thatlow temperature adhesive application can be achieved when using lowmelting point (below 100°C) polymers as packaging films, for exampleethylene vinyl acetate (EVA) copolymers, ethylene methyl acrylate (EMA)copolymers, polyethylene copolymers, polypropylene copolymers orcombinations thereof.

Yet another approach is to first form the adhesive into a finite sizeand shape, and then wrap the adhesive with a plastic film. For example,U.S. Pat. No. 6,230,890 describes a method where a mass of adhesive isfirst cooled, and thereafter packaged in a polymeric shrink wrap film.

In some processes, the adhesive mass is first pumped into a mold andthen packaged. For example, U.S. Pat. No. 5,806,285 to Rizzieri teachesa method wherein adhesive is cast in a mold to form blocks. The mold hasa plurality of holes formed therein and is lined with a thin film ofplastic material which is vacuum thermoformed onto the inner surface ofthe mold. After filling the mold with adhesive, the open top surface iscovered with a thin film of plastic material which is heat sealed to thefilm lining the interior of the mold. The mold containing the adhesivewhich is now enveloped by the film is then air cooled prior to removingthe packaged adhesive from the mold.

Another process using molds is taught in U.S. Pat. No. 5,401,455 toHatfield et al. The Hatfield et al patent describes a method forpackaging hot melt adhesive compositions using a mold in the form of apan lined with a film material which has its outer surface in contactwith a refrigerant gas or liquid heat sink. Hatfield et al teaches thatwhen molten hot melt adhesive is poured into the lined pan, the adhesiveis fused to some degree with the film. According to Hatfield et al thisin turn improves later mixing of the film with the adhesive.

Yet another process utilizing a mold is disclosed in U.S. Pat. No.5,715,654 to Taylor et al. In this process, Taylor et al teaches lininga rigid mold with a thermoplastic film which is vacuum formed into themold.

Still another process is described in U.S. Pat. No. 4,039,485 andinvolves the coextrusion of a sheath or coating surrounding a hot meltadhesive where the coextruded sheath material may be polyethylene.

Various other processes for packaging hot melt adhesives are illustratedin U.S. Pat. Nos., 5,373,682, 5,401,455, 6,155,029, 6,138,441, 5,669,207and 5,942,082.

In all of the references cited above, the material used to package theHIMPSA or other plastic material is a high molecular weight polymer, amodified high molecular weight polymer, or a combination of highmolecular weight polymers. Typical examples are high molecular weightethylene vinyl acetate (EVA) copolymer, or high molecular weightethylene-acrylate copolymer, or high molecular weight low-densitypolyethylene, or a high molecular weight metallocene or single-site orZiegler-Natta copolymer of ethylene. While these materials appear to besomewhat effective for their intended purposes, they also have readilyapparent shortcomings which have detracted from their usefulness. Thesecompositions, once melted, have a propensity under certain manufacturingconditions to not homogeneously mix with the hot melt adhesive which wasenclosed therein because of the high viscosity of the polymericmaterial. As a result, these high molecular weight materials may lead todephasing from the adhesive and therefore form lumps of crosslinked orgelled particles or char, which can clog filters and nozzles inconventional production machinery. Further, experience has shown thatthe addition of even a few percent, by weight, of these above-identifiedhigh molecular weight compositions to a typical hot melt or pressuresensitive adhesive composition has an adverse effect on the ability ofthe hot melt adhesive to form an effective bond with assorted targetsubstrates. None of the references cited above teach how to formulate afilm or coating composition in order to prevent this kind of defect.

Knowing the above shortcomings it has also been suggested to packagepressure sensitive hot melt adhesives by formulating a film or a coatingcomposition that is more easily meltable together with and/or moreeasily blendable into the molten adhesive composition itself just priorto application. The following illustrate some examples of this approach.

In EP 0957029, a coextrusion system is described where a tube ofthermoplastic material is extruded and surrounded with a coextrudedmolten film which is pinched at regular intervals to create individualpackages. The coextruded outer film is merely described as being a“non-adhesive” but it is also stated that the film composition maycontain 1-5% by weight of the adhesive product.

Another illustration of this approach is shown in U.S. Pat. No.5,865,927 where the packaging process involves: a) extruding hot meltadhesive through a die, b) spraying the surface of the extruded adhesivewith a molten film forming polymeric material, the material beingselected so that it will not detract from the properties of the adhesivecomposition when remelted therewith, c) heating the surface of thecoated adhesive at a temperature and for a period of time sufficient tore-melt the film forming polymer so as to form a continuous coatingthereof yet insufficient to melt the adhesive, and d) cooling the thuscoated adhesive mass to a temperature suitable for handling. The filmcomposition described in the ′927 patent uses an EVA copolymer or a SEBSblock-copolymer, an aromatic hydrocarbon resin, a paraffin wax, and anantioxidant/stabilizer.

Another example is described in U.S. Pat. Nos. 5,112,552, and 5,292,468,where hot melt adhesive compositions are poured into a mold in the formof a lined pan. The lining is sprayed onto the interior surface of themold. Examples of the film composition used include an EVA copolymer,polyethylene copolymers, a paraffin wax, waxy forms of antioxidants,ethylene maleic anhydride, ethylene acrylic acid and natural rubbers.

EP 0557573 discloses a packaging composition for cold-flowing hot meltadhesive compositions. The packaging composition contains a blend ofstyrene-isoprene-styrene block copolymer, an aromatic hydrocarbon resin,mineral oil, a wax, and an antioxidant/stabilizer.

U.S. Pat. Nos. 4,748,796 and 4,755,245 disclose forming a protectivecoating for an adhesive by electrostatically coating a mold or cavitywith a powder screen and then pouring molten hot melt adhesive into themold. Powder materials are described as made of a wax, or as made of apolymer, or as made of a hot melt formulation, with no further specificformulations described.

Other approaches deal with pellet coating, like in U.S. Pat. No.6,120,899, where a hot melt composition may be used to coat the pellets.The hot melt composition is described as containing a polymer,tackifying resin, and a small amount of wax. In U.S. Pat. No. 6,238,732,a pelletizing aid containing less than 10 wt % wax is used to coatadhesive pellets. In addition, several underwater pelletizing processeswhich form pellets of soft or tacky plastic products, like in U.S. Pat.No. 5,041,251, use anti-blocking agents that are applied either byextruding the pellets into a liquid emulsion containing theanti-blocking agent, or applied to the surface of the extruded pelletsafter the pellets are dried as solid particles. The anti-blocking agentis commonly a mineral powder or micronized wax powder or micronizedpolymer powder.

In some packaging processes, regardless of the form of the pieces oftacky or soft plastic material to be packaged, the material may becoated with wax, or with low molecular weight ethylene based polymer. InU.S. Pat. Nos. 5,942,304 and 5,733,645, polyethylene wax is used toimprove the cuttability of soft and tacky materials. Materials used toform a coating under these conditions, however, typically cannot beformed into a continuous film, substantially surrounding the entiresurface of the adhesive or soft plastic material pieces.

In the references cited above, if any benefit can be seen from using alower-molecular-weight film composition or using a film material, whichmight include a wax, there are also apparent shortcomings which havedetracted from their usefulness. First, wax or wax-based materials areusually too brittle to be formed into continuous films and/or to be usedas packaging films as they can not be substantially stretched, folded orpinched without creating cracks and/or breaks therein which would leadto the adhesive or soft or tacky product's leakage from inside thepackage. This cracking and/or breaking behavior can also happen due tothe intrinsic cold flow and subsequent deformation of the adhesive orplastic material during storage or shipment.

Further, none of the formulations containing a wax orlower-molecular-weight compounds described as a protective film in thereferences cited above would withstand severe shipment and storageconditions like what would be experienced under stacking pressure in acontainer on a truck, on a train or in a boat, in industrial regionswhere sunny weather conditions can be around 40° C. to 50° C., evenreaching about 60° C. as a peak temperature during several hours. Inthese conditions, a thermoplastic film would typically have a tendencyto get softer, to eventually melt, to become potentially tacky or becomeprogressively plasticized due to the presence of a low molecular weightcompound in the packaged material. This is a common failure,particularly in the adhesive industry that needs to be avoided in orderto properly handle and use the packaged plastic material. None of thereferences exhibiting a lower-molecular-weight film or coatingcomposition in the state of the art teaches how to withstand a migrationtest for a 3 mil thick film exposed during more than 3 days at 60° C.,as set forth hereinafter.

Therefore, it has long been known that it would be desirable to have animproved packaging film for enclosing pressure sensitive, cold-flowing,hot melt adhesive compositions or tacky or soft plastic materials. Thefilm material should advantageously be operable to reduce the attendantwaste produced as a result of utilizing conventional packagingtechniques, and which further reduces or substantially eliminates anytroublesome clogging or other deleterious effects which may occur whenit is used in combination with conventional adhesive applicationmachinery. Further, the packaging film should have no substantial effecton the ability of the hot melt adhesive composition to form effectivebonds on the desired substrates, and should not block to similar filmsat elevated storage and shipment temperatures. The packaging film shouldalso be inexpensive to manufacture and sell, and further becharacterized by its ease of utilization.

SUMMARY OF THE INVENTION

The present invention provides a method for packaging plastic materialslike hot melt adhesives using a wax-based polymeric film to surround theplastic material, the resulting package formed thereby, and the filmcomposition used therein. Any process to package the plastic materialcan be potentially used to form or apply the film around the plasticmaterial. The packaging film is preferably employed for surrounding orenclosing cold flowing, pressure sensitive, hot melt adhesivecompositions, but is readily adaptable for packaging other plasticcompositions. Also, the packaging film is particularly adapted to acoextrusion process, but is readily adaptable to any process where afilm is used to surround or package a plastic material, particularly ahot melt pressure sensitive adhesive composition.

In accordance with the present invention, there is provided a method forpackaging a plastic mass of material comprising the steps of providing aplastic mass of finite size and shape, and surrounding the plastic masswith a wax-based polymeric film. In accordance with a preferredembodiment for the method of the present invention, there is provided amethod for packaging a plastic mass of material, preferably a hot meltadhesive, comprising the steps of extruding a plastic mass of material,preferably a hot melt adhesive, through a die orifice, and coextruding apolymeric film to surround the plastic mass, preferably the hot meltadhesive. The wax-based polymeric film comprises a composition having atleast 25% by weight of a wax material, an enthalpy of fusion of at leastabout 100 J/g measured by DSC, and an elongation value at break of atleast about 100% measured by a conventional film tensile strength testat 2 inch/min. Any type of plastic mass and/or hot melt adhesiveformulation can be packaged or surrounded by the polymeric film. Also,the specific enthalpy of fusion desired and/or elongation value at breakdesired can be adjusted and/or obtained by blending an appropriateamount of partially crystalline ethylene-based polymer together with athermoplastic elastomeric block copolymer and/or an ethylene basedelastomer.

The polymeric film composition used preferably includes at least about25% by weight of a wax material; about 5% to about 65% by weight of apartially crystalline ethylene-based polymer comprising a homopolymer, acopolymer, a terpolymer or an interpolymer having a melt flow index of0.05 g/10 min. to 800 g/10 min. at 190° C. and a DSC melting point ofabout 40° C. to about 130° C.; about 0% to about 40% by weight of athermoplastic elastomeric block copolymer having a structure A-B, A-B-A,A-(B-A)_(n)-B, or (A-B)_(n)-Y wherein A comprises a polyvinyl aromaticblock having a Tg higher than 80° C., B comprises a rubbery midblockhaving a Tg lower than −10° C., Y comprises a multivalent compound, andn is an integer of at least 3; about 0% to about 25% by weight of anethylene-based and/or propylene-based elastomer comprising a copolymeror terpolymer having a Tg lower than −10° C.; wherein the amount ofpartially crystalline ethylene-based polymer, thermoplastic elastomericblock copolymer, and ethylene-based and/or propylene-based elastomercomprises about 30% or more of the total film composition; and whereinthe film composition has an enthalpy of fusion of at least about 100 J/gand an elongation value at break of at least about 100%. Combining thewax material and partially crystalline ethylene based polymer togetherwith an amount of a thermoplastic elastomeric block copolymer and anelastomer enables the film composition to provide a desired level ofviscosity, flexibility, temperature resistance, migration resistance,and compatibility with the adhesive formulation and still providedesired application characteristics and bonding performances.

The present invention also provides a plastic product package,preferably a hot melt adhesive package. The package includes a plasticmass such as a hot melt adhesive mass, having a finite size and shape,such as a pillow, pellet, or cylindrical shape, and a polymeric filmhaving a wax-based composition as defined above which surrounds theplastic mass or hot melt adhesive mass. Preferably, the polymeric filmhas a thickness of 10 microns to 1,000 microns.

An advantage of the polymeric film composition of the present inventionis that it can be used to package virtually any type of material such asa plastic composition, and particularly a pressure sensitive hot meltadhesive. Another advantage is that the polymeric film composition maybe melted and combined with the plastic material, especially when thematerial is a hot melt adhesive composition, during the manufacturingprocess, thereby eliminating any waste packaging issues. A furtheradvantage is that the packaging film of the present invention, whencombined with a hot melt adhesive composition in a melting pot duringthe manufacturing application process, is substantially compatible withthe adhesive composition itself and therefore does not have anysubstantial deleterious effects on the physical, or performancecharacteristics, of the hot melt adhesive composition and does notsubstantially adversely impact the operation of hot melt applicationequipment. Another important advantage of the present film compositionis that it is substantially resistant to migration therethrough of lowmolecular weight compounds from the adhesive and/or plastic mass itsurrounds or from any external source it might contact, and thereforeresults in a package which is substantially non-blocking when exposed toenvironmental conditions, typically 104° F., 122° F. or 140° F. for afew hours to about 7 days or more.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a DSC graph of temperature versus heat flow for filmcomposition formula 1601-110F in accordance with the present invention;

FIG. 2 is a DSC graph of temperature versus heat flow for filmcomposition formula 1601-155E in accordance with the present invention;

FIG. 3 is a DSC graph of temperature versus heat flow for filmcomposition 1601-00B which is outside the desired performancecharacteristics for a packaging film in accordance with the presentinvention; and

FIG. 4 is a DSC graph of temperature versus heat flow for filmcomposition 1601-156B which is outside the desired performancecharacteristics for a packaging film in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The polymeric wax-based film composition of the present invention may beutilized to package virtually any type of plastic material (alsooftentimes referred to in this description as a “plastic mass”),especially compositions and compounds, particularly polymers, that aresoft, pliable and/or tacky at an ambient temperature of 60° F. Asexamples, the polymer film composition disclosed herein may be used topackage thermoplastic compositions, and is especially intended forpackaging hot melt adhesives prepared from polymers, copolymers,terpolymers and interpolymers, block copolymers, elastomers,polyolefins, polyurethanes, styrene, acrylics, vinyl acetates, andpolyvinyl alcohol or combinations thereof. More specific examplesinclude hot melt adhesives prepared from (1) rubber polymers such asblock copolymers of monovinyl aromatic hydrocarbons and conjugateddienes, e.g., styrene-butadienes (SB), styrene-butadiene-styrene (SBS),styrene-isoprene-styrene (SIS), styrene-ethylene-butylene-styrene (SEBS)and styrene-ethylene-propylene-styrene (SEPS); (2) ethylene-vinylacetate polymers, ethylene esters and copolymers, e.g. ethylenemethacrylate, ethylene n-butyl acrylate and ethylene acrylic acid; (3)polyolefins, e.g. polyethylene and polypropylene; (4) polyvinyl acetateand random copolymers thereof; (5) polyacrylates; (6) polyamides; (7)polyesters; (8) polyvinyl alcohols and copolymers thereof; (9)polyurethanes; (10) polystyrenes; (11) polyepoxides; (12) graftcopolymers of vinyl monomers and polyalkylene oxide polymers; and (13)aldehyde containing resins such as phenol-aldehyde, urea-aldehyde,malemine-aldehyde and the like. The polymeric wax-based filmcomposition, however, is not limited to packaging thermoplasticcompositions like hot melt adhesives, and the term “plastic” is intendedto be much broader in scope. A more complete listing of plasticmaterials including hot melt adhesive compositions can be foundhereinafter in this description.

The polymeric film composition can be utilized with virtually anypackaging process where a film is surrounding a plastic material,especially a soft, pliable and/or tacky material such as a hot meltcomposition, and specifically a hot melt adhesive composition. Thus, thepolymeric film composition of the present invention can be utilized withplastic materials which are packaged by extrusion, coextrusion, trays,molds, as well as form, fill, and seal technologies, spray coating, orby any other specific technique, such as those described in the priorart. In fact, the polymeric film composition described herein could evenbe utilized with hand-wrapping processes. Thus, the polymeric filmdescribed herein can be formed simultaneously with the plastic material,as for example in a coextrusion process, or it can be formed separately,stored in roll form and later utilized to package the plastic material,as for example in trays, molds or form, fill and seal technologies. Inthe latter situation, the film material can be formed into a film (e.g.by extrusion), rolled, stored, shipped and then unwound to package theplastic material.

As used herein, the term “plastic material” or “plastic mass” isintended to describe any natural or synthetic matter, compound orcomposition that is flowable with or without the application of heatthereto, and that can be molded, cast, squeezed or pressed into variousshapes. Thus, the term “plastic material” or “plastic mass” encompasses,but is not limited to, soft and pliable matter, thermoplasticcompositions and thermoplastic compounds (e.g. thermoplastic polymers),thermosetting compositions and thermosetting compounds (e.g.thermosetting polymers), hot melt compositions and hot melt compounds(e.g. polymers used in hot melts), as well as hot melt adhesivecompositions and hot melt adhesive compounds (e.g. polymers used in hotmelt adhesives), and blends of the above materials. It should thus benoted that the terms “plastic mass” and “plastic material” are intendedto be broader than what has been called “plastics” as the term“plastics” is typically used to denote mixtures of materials (i.e. acomposition), one of which is a natural or synthetic polymer, that arecapable of being formed into a fiber, sheet or solid, or cast in a mold,at one stage of processing and subsequently becoming more rigid atanother stage.

As used herein, the term “thermoplastic composition” refers to anyaggregate, mixture, mass or body formed by combining two or moreingredients which employs a thermoplastic compound as one or morecomponent thereof, and which has the property of softening and becomingmoldable when heated and of hardening and becoming relatively more rigidagain when cooled, although the degree of rigidity and hardness may varywidely. A thermoplastic compound is any material that becomes or remainssoft and moldable when subjected to heat, and becomes harder andrelatively more rigid again when cooled, although the degree of rigidityand hardness may vary widely. Typical examples of thermoplasticcompounds include any plasticizer, polymer, pre-polymer, terpolymer,interpolymer, monomer or oligomer intended to be transformed or to beadded to an end-used product, or to be a raw material for a synthetic orchemical process. Typical thermoplastic compounds include, but are notlimited to, acrylonitrile-butadiene-styrene (ABS), acetyls, acrylics,cellulose acetates, cellulose acetate butyrates, nylons, polycarbonates,polyethylenes, polystyrenes, polyvinyl chlorides, polyvinylidenechlorides and tetrafluoroethylenes. The term “thermosetting composition”refers to any aggregate, mixture, mass or body formed by combining twoor more ingredients which employs a thermosetting compound as one ormore component thereof, and which has the property of becomingpermanently hard and rigid when heated or cured. A thermosettingcompound is any material that becomes permanently hard and unmoldablewhen heated or cured. Typical thermosetting compounds include, but arenot limited to, alkyds, allylics, epoxies, melamines, ureas, phenolics,polyesters, silicones, and urethanes. The term “hot melt composition” isused to refer to any aggregate, mixture, mass or body formed bycombining two or more ingredients and containing thermoplastic materialsespecially thermoplastic polymers which typically exist as solid massesat ambient temperature and can be converted to a flowable liquid by thedirect or indirect application of heat. Such hot melt compositionstypically contain a thermoplastic polymer blended together with variousconventional ingredients such as plasticizers, waxes, fillers andstabilizers/antioxidants. A “hot melt compound” refers to any of theindividual ingredients of a hot melt composition, particularly thepolymer component thereof. The term “hot melt adhesive composition”refers to a hot melt composition which is fuirther formulated withtackifying resins in order to improve adhesion and introduce tack intothe composition. Such tackifying resins are well known in the art andwill be fuirther described hereinafter in this description. A “hot meltadhesive compound” refers to any of the individual ingredients of a hotmelt adhesive composition, particularly the polymer or resin componentsthereof. Thermoplastic compositions, thermosetting compositions, hotmelt compositions, and hot melt adhesive compositions are useful in themanufacture of a variety of goods. For example, hot melt adhesives arespecifically useful in the manufacture of disposable non-woven articleswhere bonding of substrates is often necessary, such as disposablediapers, hospital pads, sanitary napkins, panty shields, surgical drapesand adult incontinent briefs. Other diversified applications involvepaper products, packaging materials, tapes and labels. In theseapplications, the hot melt adhesive is heated to its molten state andthen applied to a substrate. If a laminate is desired, a secondsubstrate may then be brought into contact against the first substrateto form the laminate. The major advantage of hot melt adhesives is thelack of a liquid carrier, as would be the case of water or solvent basedadhesives thereby eliminating costly processes associated with liquidcarrier removal.

Although the polymeric film composition of the present invention can beutilized with virtually any packaging process, it is particularlyadapted for a coextrusion process. In a coextrusion process, the plasticmaterial to be packaged is generally melt blended in a mixer and thensqueezed or extruded through an appropriately sized orifice in a diewhile still at a temperature above or very close to the softening pointof the material. The orifice and die may be of any conventionalconfiguration and generally is such as to provide either a slot like orcylindrical like configuration for the plastic material as it is pumpedthrough the orifice. The temperature of the die must be maintained wellabove the melting point of the plastic material, and is typically in therange of 100° C. to 215° C. In coextrusion, the polymeric wax-based filmmaterial of the above-identified invention is then simultaneouslyextruded from the die to surround the plastic material to be packagedand thus forms a sheath or wrapping which encloses the material to bepackaged. Coextrusion techniques are well known in the art, and suitableequipment for coextrusion processes are described for example in EP0957029, in U.S. Pat. No. 5,527,491, in U.S. Reissue RE 36,177, and inU.S. Pat. No. 5,942,304. As is well known, since the materials beingextruded are at elevated temperatures, the coextrusion process typicallyoccurs under water so that the plastic material and film that surroundsthe material begins to cool immediately after being extruded from thedie. Thereafter, the plastic material covered by the polymeric film isallowed to cool either in a water bath, or in a refrigerant medium suchas chilled glycol, liquid or gaseous nitrogen, compressed carbon dioxideor the like, or under ambient conditions so that the wrapped plasticmass is sufficiently cooled for handling. The coated extrudate can thenbe pinched mechanically (either when still at an elevated temperature orafter cooling to a desired temperature) into a unit of desired size,shape, weight and/or portion using conventional equipment such asrollers, and subsequently sealed if necessary. The seal can be ahermetic seal, or a mechanical seal depending upon the size, shape,weight, and/or portion of the unit, but in any event, should besufficient to prevent leaking of the plastic material during handling,storage or shipment. Finally, the coated unit mass of plastic materialcan be cut mechanically or by any other conventional means intoindividual packaged units using conventional equipment such as waterjet, laser or a hot knife.

The resultant packaged plastic mass may be further packaged in acontainer or bag to reduce its exposure to the environment, moisture, orother contaminants, if necessary or desired. The container or bag couldbe made of the polymeric wax-based film composition of the presentinvention or of other film compositions, but if made from other filmcompositions, such container or bag may then need to be removed byconventional procedures prior to utilization of the individual coatedplastic units contained therein, especially if the individual packagedplastic units contain a hot melt adhesive composition intended for usein a melt tank. In contrast, if made of the polymeric wax-based filmcomposition of the present invention, the container or bag could bemeltable together with and blendable into the molten adhesive itselfjust prior to application.

The polymeric wax-based film material described herein can be utilizedwith a plastic material or mass, such as a thermoplastic composition, athermosetting composition, a hot melt composition, or a hot meltadhesive composition of any desired size, shape, weight and/or portionto provide a packaged unit. Thus, the packaged unit may be in the formof bricks, blocks, pillows, cartridges, pellets, cylinders, ribbons, orthe like. In addition, although it is preferable that the polymeric filmof the present invention be compatible with the plastic material whichit surrounds, it is not absolutely necessary. Typically, however, thepolymeric film composition should have physical characteristics whichare compatible with and do not substantially adversely affect theinherent characteristics of a molten mixture of the plastic mass and thepolymeric film material, and further the polymeric film material whenmelted together with the plastic mass which it surrounds to form amixture is substantially compatible with the operation of applicationequipment. When the plastic mass is a hot melt adhesive composition, thepolymeric film should not substantially adversely affect the adhesivecharacteristics. However, in certain applications, it may be desirableto simply unwrap the packaged plastic mass prior to use, in which casethe polymeric film wrapping could be discarded if desired. Normally,however, the polymeric film composition should be formulated to becompatible with the plastic material it packages so that the polymericfilm and plastic material may be blendable together in a molten mixturethat is compatible with the operation of application equipment and thatdoes not adversely affect the inherent (especially adhesive)characteristics of the material.

The polymeric film used as the skin material can be colored using anydesired pigment or may be printed on using any known printing techniqueor in general be compounded with any usefuil ingredient therein which iscompatible therewith.

The Hot Melt Adhesive

The method and polymeric film composition of the present invention isadaptable to the packaging of virtually any type of plastic material,especially a thermoplastic composition, thermosetting composition, hotmelt composition and/or hot melt adhesive composition. It is especiallyadapted to the packaging of hot melt adhesives, and specifically hotmelt pressure sensitive adhesives where the handling problems are mostsevere. As is well known, hot melt adhesives comprise a blend of variouscompatible ingredients and typically includes a blend of a polymerand/or copolymer, tackifying resin, plasticizer, filler, wax and anantioxidant. Examples of typically formulations can be found in U.S.Pat. No. 5,149,741 and U.S. Reissue Patent RE 36,177.

Any of a variety of well known and readily available thermosettingmaterials can be used as the polymer, copolymer or in blends of polymersand/or copolymers in the adhesive compositions. Examples of suchmaterials include polyacrylates, polyesters, polyurethanes,polyepoxides, graft copolymers of one or more vinyl monomers andpolyalkylene oxide polymers, aldehyde containing resins such asphenol-aldehyde, urea-aldehyde, melamine-aldehyde and the like, as wellas polyamides.

Any of a variety of well known and readily available thermoplasticmaterials can also be used as the polymer, copolymer or in blends ofpolymers and/or copolymers in the adhesive compositions. Examples ofsuch materials include ethylene based polymers, including ethylene vinylacetate, ethylene acrylate, ethylene methacrylate, ethylene methylacrylate, ethylene methyl methacrylate, an ethylene-styrene interpolymer(ESI), an ethylene acrylic acid, ethylene vinyl acetate carbon monoxide,and ethylene N-butyl acrylate carbon monoxide; polybutene-1 polymers;polyolefins such as high and low density polyethylene; polyethyleneblends and chemically modified polyethylene, copolymers of ethylene andC₁-C₆ mono-or di-unsaturated monomers; polyamides; polybutadiene rubber;polyesters such as polyethylene terephthalate, and polybutyleneterephthalate; thermoplastic polycarbonates; atactic polyalphaolefins,including atactic polypropylene, polyvinylmethylether and others;thermoplastic polyacrylamides, such as polyacrylonitrile, and copolymersof acrylonitrile and other monomers such as butadiene styrene;polymethyl pentene; polyphenylene sulfide; aromatic polyurethanes;polyvinyl alcohols and copolymers thereof, polyvinyl acetate and randomcopolymers thereof; styrene-acrylonitrile,acrylonitrile-butadiene-styrene, styrene-butadiene rubbers,acrylonitrile-butadiene-styrene elastomers, A-B, A-B-A, A-(B-A)_(n)-B,(A-B)_(n)-Y block copolymers wherein the A block comprises a polyvinylaromatic block such as polystyrene, the B block comprises a rubberymidblock which can be polyisoprene, and optionally hydrogenated, such aspolybutadiene, Y comprises a multivalent compound, and n is an integerof at least 3, and mixtures of said substances. Examples of these latterblock copolymers including styrene-butadiene, styrene-butadiene-styrene,styrene-isoprene-styrene, styrene-ethylene-butylene-styrene andstyrene-ethylene propylene-styrene.

While the total styrene content of the polymers can be as much as 51wt-% of the polymer, and since the polymers can have more than two Ablocks for optimal performance, the total A block should be less than orequal to about 45 wt-% of the polymers, and, most preferably, is lessthan or equal to 35 wt-% of the polymer. In an S-B-S(styrene-butadiene-styrene) copolymer, the preferred molecular weight isabout 50,000 to 120,000, and the preferred styrene content is about 20to 45 wt-%. In an S-I-S (styrene-isoprene-styrene) copolymer, thepreferred molecular weight is about 100,000 to 200,000 and the preferredstyrene content is about 14-35 wt-%. Hydrogenating the butadienemidblocks produces rubbery midblocks that are typically converted toethylene-butylene midblocks.

Such block copolymers are available from Kraton Polymers, Enichem,Atofina Elastomers and Dexco. Multiblock or tapered block copolymers(the A-(B-A)_(n)-B type) are available from Firestone.

Other polymers that could be used are syndiotactic polypropylene (SPP)polymers or isotactic polypropylene random copolymers (RCP) and/orblends of SPP or RCP with amorphous atactic poly-(α-olefins (APAO), allof which are well known in this art. The SPP polymers are essentiallyhigh molecular weight stereospecific propylene homopolymers orcopolymers of propylene with other α-olefin monomers such as ethylene,butene-1 or hexene-1. RCPs comprise a random copolymer of propylene andan CL-olefin having the formula R—CH═CH₂ where R is hydrogen or a C₂ toC₁₀ alkyl group, preferably ethylene. The useful RCP polymers for thepresent invention are preferably metallocene catalyzed (MRCP) orsingle-site catalyzed and will contain at least 1.5% by weight of thesaid α-olefin comonomer, and having a melting point of about 145° C. orlower, as measured by DSC method, a melt flow rate of 1 to 500 g/10 min.per ASTM Method D-1238, and a solid density of 0.880 to 0.905 g/cc perASTM Method D-1505. APAO polymers are a family of essentially amorphouslow molecular weight homopolymers of propylene or copolymers ofpropylene with ethylene and/or butene and/or hexene.

The tackifying resins which are used in the adhesives of the presentinvention are those which extend the adhesive properties and improve thespecific adhesion of the polymer. As used herein, the term “tackifyingresin” includes:

(a) natural and modified rosin such as, for example, gum rosin, woodrosin, tall-oil rosin, distilled rosin, hydrogenated rosin, dimerizedrosin and polymerized rosin;

(b) glycerol and pentaerythritol esters of natural and modified rosins,such as, for example, the glycerol ester of pale wood rosin, theglycerol ester of hydrogenated rosin, the glycerol ester of polymerizedrosin, the pentaerythritol ester of pale wood rosin, the pentaerythritolester of hydrogenated rosin, the pentaerythritol ester of tall oil rosinand the phenolic modified pentaerythritol ester of rosin;

(c) polyterpene resins having a softening point, as determined by ASTMmethod E28-58T, of from about 60° C. to 140° C., the latter polyterpeneresins generally resulting from the polymerization of terpenehydrocarbons, such as the monoterpene known as pinene, in the presenceof Friedel-Crafts catalysts at moderately low temperatures; alsoincluded are the hydrogenated polyterpene resins;

(d) copolymers and terpolymers of natural terpenes, e.g.styrene/terpene, α-methyl styrene/terpene and vinyl toluene/terpene;

(e) phenolic-modified terpene resins such as, for example, the resinproduct resulting from the condensation, in an acidic medium, of aterpene and a phenol;

(f) aliphatic petroleum hydrocarbon resins having Ring and Ballsoftening points of from about room temperature to 140° C., the latterresins resulting from the polymerization of monomers consistingprimarily of olefins and diolefins; also included are the hydrogenatedaliphatic petroleum hydrocarbon resins; examples of such commerciallyavailable resins based on a C₅-olefin fraction of this type are“Wingtack 95” and “Wingtack 115” tackifying resins sold by Goodyear Tireand Rubber Company;

(g) aromatic petroleum hydrocarbons and the hydrogenated derivativesthereof;

(h) aliphatic/aromatic petroleum derived hydrocarbons and thehydrogenated derivatives thereof.

Mixtures of two or more of the above described tackifying resins may berequired for some formulations. An example of a commercially availabletackifying resin which is useful for the present invention includes theresin which is identified commercially by the trade designation Escorez5600. This resin is a partially hydrogenated aliphatic aromatichydrocarbon resin, and is available from Exxon Mobil Chemical Company.

A plasticizer can also be present in the adhesive composition in orderto provide desired viscosity control without substantially decreasingthe adhesive strength or the service temperature of the adhesive. Asuitable plasticizer may be selected from the group which not onlyincludes the usual plasticizing oils, such as mineral oil, but alsoolefin oligomers and low molecular weight polymers, glycol benzoates, aswell as vegetable and animal oil and derivatives of such oils. Thepetroleum derived oils which may be employed are relatively high boilingtemperature materials containing only a minor proportion of aromatichydrocarbons. In this regard, the aromatic hydrocarbons shouldpreferably be less than 30%, and more particularly less than 15%, byweight, of the oil. Alternately, the oil may be totally non-aromatic.The oligomers may be polypropylenes, polybutenes, hydrogenatedpolyisoprene, hydrogenated butadiene, or the like having averagemolecular weights between about 100 and about 10,000 g/mol. Suitablevegetable and animal oils include glycerol esters of the usual fattyacids and polymerization products thereof. Other plasticizers may beused provided they have suitable compatibility. Kaydol, a USP gradeparaffinic mineral oil manufactured by Crompton Corporation, has alsobeen found to be an appropriate plasticizer. As will be appreciated,plasticizers have typically been employed to lower the viscosity of theoverall adhesive composition without substantially decreasing theadhesive strength and/or the service temperature of the adhesive. Thechoice of plasticizer can be useful in formulation for specific end uses(such as wet strength core applications).

Waxes can also be used in the adhesive composition, and are used toreduce the melt viscosity of the hot melt construction adhesives withoutappreciably decreasing their adhesive bonding characteristics. Thesewaxes also are used to reduce the open time of the composition withoutaffecting the temperature performance. Among the useful waxes are:

(1) low molecular weight, that is, 1000-6000 g/mol, polyethylene havinga hardness value, as determined by ASTM method D-1321, of from about 0.1to 120 and ASTM softening points of from about 150° to 250° F.:

(2) petroleum waxes such as paraffin wax having a melting point of fromabout 130° to 170° F. and microcrystalline wax having a melting point offrom about 135° to 200° F., the latter melting points being determinedby ASTM method D127-60;

(3) atactic polypropylene having a Ring and Ball softening point of fromabout 120° to 160° C.;

(4) synthetic waxes made by polymerizing carbon monoxide and hydrogensuch as Fischer-Tropsch wax; and

(5) polyolefin waxes. As used herein, the term “polyolefin wax” refersto those polymeric or long-chain entities comprised of olefinic monomerunits. These materials are commercially available from Eastman ChemicalCo. under the trade name “Epolene.” The materials which are preferred touse in the compositions of the present invention have a Ring and Ballsoftening point of 200° F. to 350° F.

(6) metallocene catalyzed propylene-based wax like those commercializedby Clariant under the name “Licocene”.

(7) metallocene catalyzed wax or single-site catalyzed wax like forexample those described in U.S. Pat. Nos. 4,914,253, 6,319,979 or WO97/33921 or WO 98/03603. As should be understood, each of these waxdiluents is solid at room temperature. Other useful substances includehydrogenated animal, fish and vegetable fats and oils such ashydrogenated tallow, lard, soya oil, cottonseed oil, castor oil,menhadin oil, cod liver oil, etc., and which are solid at ambienttemperature by virtue of their being hydrogenated, have also been foundto be useful with respect to functioning as a wax diluent equivalent.These hydrogenated materials are often referred to in the adhesivesindustry as “animal or vegetable waxes.”

The adhesive also typically includes a stabilizer or antioxidant. Thestabilizers which are useful in the hot melt adhesive compositions ofthe present invention are incorporated to help protect the polymersnoted above, and thereby the total adhesive system, from the effects ofthermal and oxidative degradation which normally occurs during themanufacture and application of the adhesive as well as in the ordinaryexposure of the final product to the ambient environment. Suchdegradation is usually manifested by a deterioration in the appearance,physical properties and performance characteristics of the adhesive. Aparticularly preferred antioxidant is Irganox 1010, atetrakis(methylene(3,5-di-teri-butyl-4-hydroxyhydrocinnamate))methanemanufactured by Ciba-Geigy. Among the applicable stabilizers are highmolecular weight hindered phenols and multifunctional phenols, such assulfur and phosphorus-containing phenols. Hindered phenols are wellknown to those skilled in the art and may be characterized as phenoliccompounds which also contain sterically bulky radicals in closeproximity to the phenolic hydroxyl group thereof. In particular,tertiary butyl groups generally are substituted onto the benzene ring inat least one of the ortho positions relative to the phenolic hydroxylgroup. The presence of these sterically bulky substituted radicals inthe vicinity of the hydroxyl group serves to retard its stretchingfrequency and correspondingly, its reactivity; this steric hindrancethus providing the phenolic compound with its stabilizing properties.Representative hindered phenols include:

1,3,5-trimethyl-2,4,6-tris(3-5-di-tert-butyl-4-hydroxybenzyl) benzene;

pentaerythritol tetrakis-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate;

n-octadecyl-3(3,5-ditert-butyl-4-hydroxyphenyl) propionate;

4,4′-methylenebis(4-methyl-6-tert butylphenol);

4,4′-thiobis(6-tert-butyl-o-cresol);

2,6-di-tert-butylphenol;

6-(4-hydroxyphenoxy)-2,4-bis(n-ocytlthio)-1,3,5-triazine;

2,4,6-tris(4-hydroxy-3,5-di-tert-butyl-phenoxy)-1,3,5-triazine;

di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate;

2-(n-octylthio)ethyl-3,5-di-tert-butyl-4-hydroxybenzoate; and

sorbitol hexa-(3,3,5-di-tert-butyl-4-hydroxy-phenyl) propionate.

The performance of these stabilizers may be further enhanced byutilizing, in conjunction therewith; (1) synergists such as, forexample, as thiodipropionate esters and phosphites; and (2) chelatingagents and metal deactivators as, for example,ethylenediaminetetraacetic acid, salts thereof, anddisalicylalpropylenediimine.

The adhesive composition useful in the method of the present inventionmay be produced using any of the techniques known in the art. Arepresentative example of the prior art procedure involves placing allof the substances, in a jacketed mixing kettle, and preferably in ajacketed heavy duty mixer of the Baker-Perkins or Day type, and which isequipped with rotors, and thereafter raising the temperature of thismixture to a range of about 250° F. to 350° F. It should be understoodthat the precise temperature to be used in this step would depend on themelting point of the particular ingredients. The resulting adhesivecomposition is agitated until the polymers completely dissolve. A vacuumis then applied to remove any entrapped air.

Optional additives may be incorporated into the adhesive composition inorder to modify particular physical properties. These additives mayinclude colorants, such as titanium dioxide and fillers such as talc andclay, crosslinking agents, nucleating agents, reactive compounds,fire-retardant mineral or organic agents, as well as ultraviolet light(UV) absorbing agents and UV fluorescing agents.

The Polymeric Packaging Film

The polymeric film composition of the present invention used as theimproved packaging film includes (a) at least 25% by weight of a waxmaterial; (b) about 5% to about 65% by weight of a partially crystallineethylene-based polymer comprising a homopolymer, a copolymer, aterpolymer or an interpolymer having a melt flow index of 0.05 g/10 min.to 800 g/10 min. at 190° C. and a DSC melting point of 40° C. to 130°C.; (c) about 0% to about 40% by weight of a thermoplastic elastomericblock copolymer having a structure A-B, A-B-A, A-(B-A)_(n)-B, or(A-B)_(n)-Y wherein A comprises a polyvinyl aromatic block having a Tghigher than 80° C., B comprises a rubbery midblock having a Tg lowerthan −10° C., Y comprises a multivalent compound, and n is an integer ofat least 3; (d) about 0% to about 25% by weight of an elastomercomprising a copolymer or terpolymer having a Tg lower than −10° C.wherein the elastomer may be an ethylene-based elastomer, apropylene-based elastomer or a blend of ethylene-based andpropylene-based elastomers; (e) wherein the amount of partiallycrystalline ethylene-based polymer, thermoplastic elastomeric blockcopolymer, and elastomer comprises about 30% or more of the total filmcomposition; and (f) wherein the film composition has an enthalpy offuision of at least about 100 J/g measured by DSC, and an elongationvalue at break of at least about 100% measured by a conventional filmtensile strength test at 2 inch/min

The wax material component of the packaging film comprises at leastabout 25% by weight of the packaging film composition. More preferably,the wax material comprises at least about 40% by weight of the filmcomposition with a typical range being about 25% by weight to about 65%by weight.

Among the useful wax materials are:

(1) Low molecular weight, that is, 100-6000 g/mol, polyethylene having ahardness value, as determined by ASTM method D-1321, of from about 0.1to 120 and ASTM softening points of from about 150° to 250° F.;

(2) Petroleum waxes such as paraffin wax having a melting point of fromabout 130° to 170° F. and microcrystalline wax having a melting point offrom about 135° to 200° F., the latter melting points being determinedby ASTM method D127-60;

(3) atactic polypropylene having a Ring and Ball softening point of fromabout 120° to 160° C.;

(4) metallocene catalyzed propylene-based wax like those commercializedby Clariant under the name “Licocene”.

(5) metallocene catalyzed wax or single-site catalyzed wax like forexample those described in U.S. Pat. Nos. 4,914,253, 6,319,979 or WO97/33921 or WO 98/03603.

(6) synthetic waxes made by polymerizing carbon monoxide and hydrogensuch as Fischer-Tropsch wax; and

(7) polyolefin waxes. As used herein, the term “polyolefin wax” refersto those polymeric or long-chain entities comprised of olefinic monomerunits. These materials are commercially available from Eastman ChemicalCo. under the trade name “Epolene.” The materials which are preferred touse in the compositions of the present invention have a Ring and Ballsoftening point of 200° F. to 350° F. As should be understood, each ofthese waxes is solid at room temperature. Other useful substancesinclude hydrogenated animal, fish and vegetable fats and oils such ashydrogenated tallow, lard, soy oil, cottonseed oil, castor oil, menhadinoil, cod liver oil, etc., and which are solid at ambient temperature byvirtue of their being hydrogenated, have also been found to be usefulwith respect to functioning as a wax material equivalent. Thesehydrogenated materials are often referred to in the adhesives industryas “animal or vegetable waxes”.

The preferred wax material is a paraffin wax having a melting point of60° C. to 70° C., a hard wax such as Paraflint Hi commercialized bySasol-Schuman, or Bareco PX 100 commercialized by Bareco, those hardwaxes having a hardness dmm at 23° C. of about 2 dmm or less and amelting point of 75° C. to 120° C., or blends of a paraffin wax and ahard wax. The preferred hard wax has a melting point lower than 95° C.The term “hard wax” refers to any low molecular weight, highlycrystalline ethylene-based polymer.

The partially crystalline ethylene-based polymer component of thepackaging film comprises about 5% to about 65% by weight of thepackaging film composition. More preferably, the partially crystallineethylene-based polymer comprises about 15% to about 50% by weight of thepackaging film. This partially crystalline ethylene-based polymercomponent may be a homopolymer, copolymer, terpolymer, interpolymerand/or blends thereof having a melt flow index under 2.16 kg at 190° C.of 0.05 g/10 min to 800 g/10 min, but preferably below 30 g/10 min andmost preferably below 7 g/10 min. In addition, this ethylene-basedpolymer component has a DSC melting point of 40° C. to 130° C., but apreferred melting point below 100° C.

Among the useful partially crystalline ethylene-based polymers are:LDPE, VLDPE, LLDPE, MDPE obtained by ziegler natta catalystpolymerization, or LDPE, EVA, EAA, EMA, EBA, EE2HA, obtained by gasphase random polymerization, or EO, EP, EB, EH, ESI copolymers, obtainedby ziegler natta catalyst polymerization or single-site catalystpolymerization or metallocene catalyst polymerization.

One of the preferred polymers is EMA which is readily commerciallyavailable as for example from Atofina under the trade designationLotryl.

Another preferred polymer is single site catalyzed or metallocenecatalyzed polymer which is readily commercially available as for examplefrom The Dow Chemical Company under the trade designation Affinity.

The thermoplastic elastomeric block copolymer component of the packagingfilm comprises about 0% to about 40% by weight of the packaging filmcomposition. More preferably, the elastomeric block co-polymer comprisesless that about 15% of the packaging film composition. In addition, theelastomeric block copolymer preferably has a melt flow index lower than15 g/10 min under 2.16 kg at 190° C.

Among the useful elastomeric block copolymers are those having structureA-B, A-B-A, A-(B-A)_(n)-B, or (A-B)_(n)-Y wherein A comprises apolyvinyl aromatic block having a Tg higher than 80° C., B comprises arubbery midblock having a Tg lower than −10°C., Y comprises amultivalent compound, and n is an integer of at least 3. Examples ofthese latter block copolymers including styrene-butadiene (SB),styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS),styrene-isoprene (SI), styrene-ethylene-butylene-styrene (SEBS),styrene-ethylene-butylene (SEB) styrene-ethylene propylene-styrene(SEPS) and styrene-ethylene propylene (SEP).

While the total styrene content of the polymers can be as much as 51wt-% of the polymer, and since the polymers can have more than two Ablocks for optimal performance, the total A block should be less than orequal to about 45 wt-% of the polymers, and, most preferably, is lessthan or equal to 35 wt-% of the polymer. In an S-B-S(styrene-butadience-styrene) copolymer, the preferred molecule weight isabout 50,000 to 120,000, and the preferred styrene content is about 20to 45 wt-%.

In an S-I-S (styrene-isoprene-styrene) copolymer, the preferredmolecular weight is about 100,000 to 200,000 and the preferred styrenecontent is about 14-35 wt-%. Hydrogenating the butadiene midblocksproduces rubbery midblocks that are typically converted toethylene-butylene midblocks.

Such block copolymers are available from Kraton Polymers, Enichem,Atofina Elastomers and Dexco. Multiblock or tapered block copolymers(the A-(B-A)_(n)-B type) are available from Firestone.

The preferred elastomeric block copolymer is SEBS available from KratonPolymers under the trade designation Kraton G.

The elastomer component of the packaging film comprises about 0% byweight to about 25% by weight of the packaging film composition. Mostpreferably, the elastomer comprises about 15% by weight or less of thepackaging film composition, and comprises a copolymer or terpolymerhaving a Tg lower than −10° C. The elastomer may be an ethylene-basedelastomer, a propylene-based elastomer, or blends of ethylene-basedand/or propylene-based elastomers. The term “ethylene-based” refers toan elastomer where ethylene comprises a portion thereof, and especiallywhere ethylene is the predominant group by weight, and the term“propylene-based” refers to an elastomer where propylene comprises aportion thereof, and especially where propylene is the predominant groupby weight, in the polymer.

Among the useful elastomers are EPR rubber, EPDM rubber and/or blends ofEPR and EPDM. The term EPR, as used herein, refers to elastomericcopolymers of ethylene and propylene, or such copolymers modified withfunctional monomers. The functional monomers include a class ofunsaturated organic compounds containing one or more functional groupsincluding carboxylic acid group (—COOH), anhydride group (—CO—O—CO—),hydroxyl group (—OH), ether group (—OR, R is a hydrocarbon radical),primary, secondary and tertiary amine groups and ester group. Thecontent of propylene in the copolymer is in the range of 15% to 70% byweight, preferably between 20% to 45% by weight. The term EPDM refers toelastomeric terpolymers comprising of 15% to 70% by weight, preferablybetween 20% and 45% by weight, of propylene, from 20% to 80% by weightof ethylene and from 2% to 15% by weight of a diene, for example,1,4-hexadiene, norbomadiene, ethylidene-norbomene, dicyclopentadiene,butadiene and isoprene. The EPDM used here also includes functionallymodified versions of terpolymers containing the functional groups hereinmentioned above. EPR and EPDM rubbers are commercially available fromExxon Chemical Company under the Vistalon trade name and from DMSPolymers, Inc., under the Kelton trade name. Functionally modified EPDMcontaining anhydride groups are sold under the trade name Exxelor byExxon Chemical Company. As can be seen from what is disclosed above, thepreferred EPR or EPDM rubber content is between 5% to 65% by weight.Below 5% there is insufficient cohesiveness while above 65% theviscosity of the composition becomes too high. The composition mostpreferably contains 15% to 40% by weight of EPR, or EPDM, or a mixturethereof.

EPR and EPDM rubbers are readily commercially available as for exampleunder the trade designation “Vistalon” from ExxonMobil Chemical Company,“RexFlex” from Huntsman Corporation, “AdFlex” from Basell Plastics, and“Keltan” from DSM Company, Inc.

The packaging film composition also typically includes a stabilizer orantioxidant. The stabilizers which are useful in the hot meltcompositions of the present invention are incorporated to help protectthe polymers noted above, and thereby the total adhesive system, fromthe effects of thermal and oxidative degradation which normally occursduring the manufacture and application of the film composition as wellas in the ordinary exposure of the final product to the ambientenvironment. Such degradation is usually manifested by a deteriorationin the appearance, physical properties and performance characteristicsof the composition. Any of the stabilizers/antioxidants previouslydescribed herein for use with the hot melt adhesive composition may alsobe utilized in the polymeric film composition. Among applicablestabilizers, a particularly preferred antioxidant is Irganox 1010, atetrakis(methylene(3,5-di-teri-butyl-4-hydroxyhydrocinnamate))methanemanufactured by Ciba-Geigy.

The packaging film compositions of the present invention may be producedusing any of the techniques known in the art. An exemplary procedureinvolves placing the wax material and all other ingredients in ajacketed, mixing kettle, preferably in a jacketed heavy duty mixer ofthe Baker-Perkins or Day type, which is equipped with rotors andthereafter raising the temperature to a range of from about 250° to 400°F., and more preferably about 300° F. The precise temperature to be usedwill depend on the melting point of the particular ingredients. When theinitial mixture has been melted and blended, the mixture is blanketed inCO₂ at a slow flow rate and the block copolymer is added. The filmcomposition may be pelletized using conventional underwater pelletizingtechniques. Other exemplary procedures are using extrusion-compoundingwith single or double screws.

These film compositions can be easily characterized directly bydifferent conventional analytical methods or after solubilization and/orsemi-preparative liquid chromatography followed by afraction-by-fraction identification, such as Differential ScanningCalorimetry (DSC), Infra-Red (bulk or surface) spectroscopy, stericexclusion chromatography (SEC), TREF i.e. crystallinity-driven drivenfractional SEC, Nuclear Magnetic Resonance (NMR).

The viscosity of the improved packaging film of the present invention isabout 1000 to about 1,500,000 mPa.s at about 300° F. to about 375° F.,as determined by employing a Brookfield Thermocel or other appropriateviscosimeter and utilizing the testing techniques which are set forth inASTM Method D3236-73. Once mixed and equilibrated, the molten packagingfilm of the present invention can be coextruded along with thethermoplastic composition, as previously described herein, or can beformed into a film by casting or extruding the molten composition onto arelease coated surface. Commercially available machinery for performingthese manufacturing techniques may be purchased from The NordsonCompany. As earlier discussed, the packaging film enclosing the hot meltadhesive composition may be charged directly to the melt tank of acommercial hot melt application machine thereby eliminating any wasteand avoiding many of the shortcomings attendant to the use of theconventional packaging techniques discussed earlier.

The new packaging film composition may be used virtually in anypackaging techniques. For example it may be sprayed or poured ontoadhesive pieces in general, or adhesive blocks, or into molds, ortransformed into a form of package item, like a bag, a thermoformed trayor a wrapping film or sheet.

Particularly the new film composition may be processed to form a film byconventional film-extrusion or film-coextrusion techniques, likeextrusion-coating, cast-extrusion, blown-extrusion. The new filmcomposition may be compounded with conventional additives in order toimprove its processability in these traditional film forming techniques,and to improve film mechanical and physical final characteristics. Inthese processes, the film is generally extruded then stretched andcooled, slit and wound upon itself to form rolls for storage andsubsequent use in commercially available filling and wrapping machinery.In this regard, the improved packaging film of the present invention canbe utilized on semi-automatic multi-size filling and wrapping machinessuch as those manufactured under the trade designation “Mark 10I-12-Asystem: Inverted Horizontal Form, Fill and Seal Machine”, and which ismanufactured by Premier Packing Systems, Inc. of Waukesha, Wis. Othercompatible machinery may be easily selected by those skilled in the art.

EXAMPLES

Film material samples were prepared with the ingredients and mixingprocedures described herein below. A total of 250 grams each were madeand the mixing was carried out at about 300 to 400° F. under carbondioxide atmosphere in a laboratory type mixer what consists of apropeller powered by a motor, a heating mantle, a temperature controlunit and a container of about 1 pint in size. The appropriate amounts ofeach component, calculated according to the ratios shown in the tablesbelow, were added to the container in an appropriate sequence to allowmixing while limiting the heat or shear degradation of ingredients.After the ingredients in the container were completely melted and mixedthoroughly to allow a good visual homogeneity, samples were storedappropriately to be tested.

Film samples were made on a Meltex CL 104 lab-scale coater fitted withan EP-11 slot die nozzle in 2-in width and 3-mils or 6-mils thickness,coated on siliconed release paper. Temperature was from 250 to 375° F.,depending on the viscosity level of the film material, and rolling speedwas about 2 linear meters per minute. Any test performed on film sampleswas made at least 24 hours after the film was made. The term “mil”represents a thickness value of one thousandth of an inch correspondingto 25.4 ×10⁻⁶ meters.

Tensile strength of film materials were performed according to testmethod ASTM D-638 at various temperatures, typically −20° C. and 20° C.at 2 inch/min. Samples are made from 6-mils or 3-mils thick films andhave “dog-bone” curved shape with no sharp cut on the edges to initiateno tear effect during measurement. Elongation value at break is reportedas average on 3 to 5 samples. This test is aimed to simulate themechanical stress that may endure the packaged material, and the skinmaterial itself.

Blocking tests were performed in the following manner: square surfacesof 2 inch by 2 inch of film were put in contact to each other under aload pressure of about 2 psi, and put in the oven at 50, 60 or 70° C.during 4 hours, 24 hours, or 7 days. After allowing the samples to cooldown, visual observation was made if no or little or moderate or strongforce was needed by hand to separate surfaces from each other. This testis made to simulate possible weather conditions where the adhesivepackage can be stored or shipped.

Migration tests were performed on 3-mils or 6-mils films at 40, at 50 orat 60° C. Film samples are put in contact with some adhesive material.Two different adhesive compositions were selected for their content inmigrant species and their specific ability to allow migrant species togo through a film material over time. A square surface of 2 inch by 2inch of film was put in contact of a adhesive piece. The piece ofadhesive was a parallelepipedic form which larger base was 1 inch by 1inch, and height of about a quarter of an inch. The larger base of theadhesive piece is placed in the center of the film square. Another filmsquare is put on the top of the adhesive piece, and this top square ismade of a low temperature heat sealable material. With light heatprovided by a hot air gun, this material is sealed to the edges of thebottom square film, in order to contain any leakage of the adhesivepiece due to intrinsic adhesive flow with time or increased temperature.Such “pillows” are put in the oven during few days, typically 3 to 21days. When removed from the oven after a certain number of days,observations are made at room temperature visually or by finger contact:staining of the film, friction with no pressure, tack to finger or tackto itself. This test is aimed to simulate the ability of the filmmaterial to resist migration from typical hot melt compositions instorage or shipment conditions.

DSC test method was performed on film compositions in accordance withtest method ASTM D-3417, with sweeping rates of 20° C. per minutes on aDSC instrument model 2010 from TA Instruments based in New Castle, Del.Three temperature sweeps are performed consecutively on a 5 to 10 mgsample under a nitrogen atmosphere from −100° C. till 200° C., then from200° C. to −100° C., then again from −100° C. till 200° C. This lastsweep shows a reproducible measurement of the enthalpy of fusion of thefilm composition expressed in Joule per gram of material. “Enthalpy offusion” is sometimes also referred to as “melting capacity” and/or“specific heat capacity” by those skilled in this art.

Hot melt adhesive were prepared with the ingredients and mixingprocedures described herein below. A total of 2000 grams each were madeand the mixing was carried out at about 300° F. to 375° F. under carbondioxide atmosphere in a laboratory type mixer what consists of apropeller powered by a motor, a heating mantle, a temperature controlunit and a container of about 1 gallon in size. The appropriate amountsof each component, calculated according to the ratios shown in thetables below, were added to the container in an appropriate sequence toallow mixing while limiting the heat or shear degradation ofingredients. After the ingredients in the container were completelymelted and mixed thoroughly to allow a good visual homogeneity, sampleswere stored appropriately to be tested.

Dissolution tests of the skin materials into the adhesive melt wereconducted in the lab on 2000 g adhesive samples. Depending on each casestudied, a precise amount, typically 20 g or 40 g of a 6-mils-thick filmof the film material was put in the molten adhesive at the consideredadhesive application temperature, typically 275° F. to 350° F. After aperiod of 30 minutes with no movement in an air-circulating oven, visualobservation was made of the molten aspect. A smooth agitation performedby hand with a stainless steel bar at about 60 rpm during 10 roundsallowed to visually assess the dissolvability. After another 30 minutesperiod in the oven, if still non-homogeneous aspect were observedvisually or with a stainless steel bar, further agitation were conductedwith a powered 3-blades propeller at 50 rpm. Observation was made afterevery 30 minutes. Each time a dissolution test was performed, a blanksample of adhesive was taken for reference.

Brookfield viscosity was tested according to ASTM D-3236 Method atelevated temperature. Tests were performed on blank adhesive samples inthe same time as on contaminated adhesive samples produced in thedissolution test described above.

Ring & Ball softening point was determined with an automated Herzog unitaccording to ASTM E-28 method. Tests were performed on blank adhesivesamples in the same time as on contaminated adhesive samples produced inthe dissolution test described above. Adhesive formulas used for thismigration test were made according to the mixing procedure describedabove. One composition was called “high oil content adhesive”, made of22% Nyplast 222B, 57% Escorez 5600, 20% Vector 4213, 1% Irganox 1010 inweight. Another composition was called “rosin-ester containing adhesive”and was made of 18% Nyplast 222B, 59% Sylvatac RE 100, 22% Vector 4215,1% Irganox 1010 in weight.

Ageing tests of adhesive formulations were performed at 350° F. on 200 gsamples put in a loosely covered 400 g-glass jar, in a ventilated oven.Visual observations were made after 3 days at 350° F. if any char,gelling, skin, sedimentation, or dephasing occurred. Tests wereperformed on blank adhesive samples in the same time as on contaminatedadhesive samples produced in the dissolution test described above.

Laminated specimens were formed by using a Nordson Meltex CT225 hot melthigh speed coater. When spiral spray technique was used, the coater wasfitted with a 0.018 inch spiral spray extrusion nozzle available fromNordson Corporation. When slot coat technique was used, the coater wasfitted with a EP-11 slot die extrusion nozzle available from NordsonCorporation. Adhesives were spiral sprayed at various coating weights,depending on the application required, with different opentimes—typically 0.1 to 0.5 seconds—to the 1-bar-nip rolls compression.Application temperature was set between 275° F. and 350° F. depending onthe application requirements. Lamination process was performed on blankadhesive samples in the same time as on contaminated adhesive samplesproduced in the dissolution test described above.

Standard polypropylene-based spun-bond non-woven web is available fromBBA Corporation at 15.7 gram per square meter coating weight. Standardpolyethylene non-breathable white film at 17 gram per square meter isavailable under trade name DH-216 from Clopay Corporation.

Peel strength was measured in the machine direction in 180° geometrywith a tensile tester (Instron Model 55R1122) in the controlledatmospheric environment (20° C. and 50% relative humidity). Prior to thetest, the specimens were conditioned at the controlled environment forapproximately 12 hours to ensure the reproducibility and accuracy of thedata. The test was done at a cross-head speed of 12 inches/min. Theaverage peel value over the displacement of six replicates, normalizedto g/in unit, was reported as the peel strength. Tests were performed onblank adhesive samples in the same time as on contaminated adhesivesamples produced in the dissolution test described above.

Creep Resistance test was carried out with the laminated specimenscontaining elastic strands. To prepare the specimen, three elasticstrands (Lycra 151 or 262 at 740 dtex basis weight available fromDupont), which were stretched to 300% elongation, were either laminatedbetween a layer of 1.0 mil thick white or printed polyethylene film anda layer of polypropylene spunbond nonwoven fabric web. The differentparts of the laminated specimen, said films or webs and stretchedelastic strands, have been glued together by the hot melt adhesive withthe spiral spray technique, and the creep test is intended to be ameasurement of the quality of the bond effectively done by the hot meltcomposition. The specimen, cut to about 350 mm in length, was stretchedout completely and its ends were securely attached to a piece of rigidboard. A length of 300 mm was marked machine direction and the elasticstrands were cut at the marks. The specimen was then placed in anair-circulating oven at 100° F. Under these conditions, the elasticstrands under stretch can retreat to a certain distance. The distancebetween the ends was measured after four hours. The ratio of the finallength to the initial length, defined as Creep Retention and expressedin percentage (%), is a measure of the ability of the adhesive to holdthe elastic strands. Tests were performed on blank adhesive samples inthe same time as on contaminated adhesive samples produced in thedissolution test described above.

Sprayability was evaluated during the coating process on a NordsonMeltex CT225 hot melt high speed coater by observing visually theregularity of the spiral pattern shape in time and space. The coatingconditions varied depending on the adhesive sample. Tests were performedon blank adhesive samples in the same time as on contaminated adhesivesamples produced in the dissolution test described above.

Dissolution test was performed on a low viscosity SIS-based HMPSA,H2548-01, available from Bostik Findley for PSA label end-use. Thesample was then slot-coated on paper at 300° F. to get a 1-mil coating,and PSA performances were evaluated in comparison with H2548-01 with noskin material, 24 hours after the coating has been made. The SAFT valuewas measured according to test method PSTC-7 with a 1.6° C./min ramp, on1-inch per 1-inch surface area of coating laminated toward stainlesssteel with a 4.5 lbs rubber roller in one pass at low speed. The peelforce, as average value or peak value over displacement was evaluated on1-inch-wide, 5-inch-long surface laminated to stainless steel in thesame way as for SAFT test, and according to test method PSTC-1 and ASTMD3330. Loop tack value was measured according to test method ASTM D6195towards stainless steel, and average value over displacement isreported. For each of these tests, 3 replicates at least were done.

The following abbreviations are used throughout this specification:

-   -   PE—polyethylene    -   PP—polypropylene    -   LDPE—low density polyethylene    -   HDPE—high density polyethylene    -   VLDPE—very low density polyethylene    -   LLDPE—linear low density polyethylene    -   MDPE—medium density polyethylene    -   EVA—ethylene vinyl acetate    -   EAA—ethylene acrylic acid    -   EMA—ethyl methacrylate    -   EBA—ethylene butyl acrylate    -   EE2HA—ethylene-2-ethyl-hexyl-acrylate    -   E—ethylene-octene    -   EP—ethylene-propylene    -   EB—ethylene-butadiene    -   EH—ethylene-hexene    -   ESI—ethylene-styrene interpolymer    -   EPR—ethylene-propylene rubber    -   EPDM—ethylene-propylene-diene-monomer    -   SB—styrene-butadiene    -   SBS—styrene-butadiene-styrene    -   SIS—styrene-isoprene-styrene    -   SEBS—styrene-ethylene-butylene-styrene    -   SEPS—styrene-ethylene-propylene-styrene    -   SBBS—styrene-butadiene-butylene-styrene    -   SIBS—styrene-isoprene-butlylene-styrene    -   SEP—styrene-ethylene-propylene    -   APAO—atactic poly-alpha-olefins    -   SPP—synd.iotactic polypropylene    -   IPP-isotactic polypropylene    -   RCP—isotactic polypropylene random copolymers    -   MMA—methyl methacrylate

Materials used in the film compositions of the following Examples aredescribed as below:

155 PARAFFIN WAX is a 65.5° C. melting point paraffin wax and isavailable from Sasol Wax Americas, Inc.

138 PARAFFIN WAX is Paraffine 58-60 available from Total S.A.

158 PARAFFIN WAX is Paraffine 68-70 available from Total S.A.

PARAFLINT C80 is a Fisher-trops wax available from Sasol Wax Americas,Inc.

POLYWAX 655 is a synthetic polyethylene wax available from BakerPetrolite, Inc.

KAYDOL USP 35 MINERAL OIL is available from Crompton Corporation.

ESCOREZ 5320 and ECR-188 are both polycyclic tackifying resins availablefrom Exxon Mobil Chemicals.

SYLVATAC RE 100 is a rosin ester tackifying resin available from ArizonaChemicals, Inc.

WINGTACK EXTRA is a aliphatic hydrocarbon tackifying resin. It isavailable from Goodyear Chemicals, Akron, Ohio.

PICCOTEX 120 is aromatic hydrocarbon tackifying resin available fromEastman Chemical.

EVATANE 18-150 and EVATANE 28-06, LOTRYL 37EH175, LOTRYL 37EH550, LOTRYL09 MG 02, LOTRYL 15 MA 03, LOTRYL 24 MA 07, LOTRYL 24MA005, LOTRYL17BA07, LOTRYL 35 BA 320 are EVA or EMA or EBA copolymers available fromAtofina Chemicals, Inc., Philadelphia, Pa.

EPOLENE C-13 and EPOLENE C-17 are LDPE grades available from EastmanChemical.

ExxonMobil LD 202 is a LDPE available from Exxon Mobil Chemicals.

AFFINITY PL 1280, AFFINITY SM 1300, AFFINITY EG8150 are single-sitecopolymers of ethylene available from Dow Chemicals.

ELVALOY 1609 AC is an EVA copolymer available from Dupont Chemicals.

VECTOR 4411 is an SIS block-copolymer available from Dexco.

KRATON G 1650, KRATON G 1652, KRATON G-1657 are SEBS block copolymersavailable from Kraton Polymers.

IRGANOX 1010 Irganox 1010 is a hindered phenol type of antioxidantobtained from Ciba-Specialty Chemicals, Tarryton, N.Y.

The invention is further illustrated by way of the examples which areset forth below.

Example 1

Tables 1a and 1b illustrate 19 different compositions suitable for useas the polymeric outer film. Each formulation in Tables 1a and 1b had anelongation value at break of greater than 100%, and a melting capacitygreater than 100 J/g. Each formulation also had excellent migrationresistance because they had little or no tack, little or no staining andwere non-blocking under the test conditions described.

Example 2

Tables 2a and 2b illustrate 15 different compositions that areunsuitable for use as the polymeric outer film. The formulations inTables 2a and 2b were all unsuitable because they did not pass one ormore of the elongation, melting capacity or migration resistance tests.In other words, each formulation in Tables 2a and 2b have one or morecharacteristic resulting in the composition having an elongation valueat break of less than 100%, a melting capacity of less than 100 J/g, orpoor migration resistance as evidenced by excessive tack and/orstaining.

Example 3

Tables 3a and 3b illustrate a comparison of the ingredients of variousformulations and the test data obtained with regard to suitable formulasfor the outer film and unsuitable formulas based on DSC data and onmigration resistance at 50° C. Also, FIGS. 1 and 2 illustrate the DSCcurves for two acceptable compositions while FIGS. 3 and 4 illustratethe DSC curves for two unacceptable compositions. FIG. 1 illustratesheat flow versus temperature for formulation 1601-110F from which itsenthalpy of fusion is measured to be 117 Joules/gram. FIG. 2 illustratesheat flow versus temperature for formulation 1601-155E from which itsenthalpy of fusion is measured to be 109 Joules/gram. FIG. 3 illustratesheat flow versus temperature for formulation 1600-00B from which itsenthalpy of fusion is measured to be 87 Joules/gram. Finally, FIG. 4illustrates heat flow versus temperature for formulation 1601-156B fromwhich its enthalpy of fusion is measured to be 73 Joules/gram. Referenceshould also be made to Table 3b for a comparison of these measuredenthalpies of fusion. Table 3 also provides the corresponding enthalpiesof fusion calculated from the raw materials values.

Example 4

Tables 4a and 4b illustrate the dissolution of film composition 1416-75Band 1601-00A compared to a 2 mil-thick EVA film, where VA content inweight is about 3%. This film is commercially available from ArminPlastics-Jersey City, N.J. Adhesive used is H2543, a typical SIS-basedadhesive commercially available from Bostik Findley, Inc. and applied attemperature around 300° F. . This kind of EVA-based film can be used toproduce hot melt adhesive cartridges in a form-fill-and-seal process,but as seen in Tables 4a and 4b, may present problems of adhesivestability, as other formulated formulas are more compatible with theadhesive system, due to the presence of low molecular weight compoundsinto the skin material composition.

Example 5

Table 5 illustrates the adhesive properties of H2543, and demonstratesthat the peel force performances are not affected by up to 2% of theouter film material. Sprayability is also not affected by the presenceof the skin material in the adhesive formulation.

Example 6

Table 6 illustrates the adhesive properties of H2994, and demonstratesthat the elastic creep performances are not affected by up to 2% of thefilm material. H2994 is a typical SIS-based adhesive commerciallyavailable from Bostik Findley, Inc. Sprayability is also not affected bythe presence of the skin material in the adhesive formulation.

Example 7

Table 7 illustrates the adhesive properties of H2548-01, anddemonstrates that the various adhesive performances are notsignificantly deteriorated by up to 2% of the film material. H2548-01 isa typical SIS-based adhesive commercially available from Bostik Findley,Inc.

TABLE 1a enthalpy of fusion of raw suitable formulas materials (J/g)1416-75B 1601-74C 1601-82B 1601-82C 1601-82D 1601-84B 1601-84C 1601-86C1601-86H 155 PARAFFIN WAX 218.7 15 (65.5 deg C.) 138 PARAFFIN WAX 204.1(58-60 deg C.) 158 PARAFFIN WAX 211.7 15 15 40 0 15 30 15 21 (68-70 degC.) PARAFLINT C80 226.7 15 25 25 15 22 25 POLYWAX 655, 239 24 0 40PRILLED ESCOREZ 5320 0 WINGTACK EXTRA 0 ECR-188 0 EVA 18-150 60 8EVATANE 28-06 35 EPOLENE C-13 94 EPOLENE C-17 80 E82onMobil LD 202 80AFFINITY PL 1280 77.3 25 AFFINITY SM 1300 82.1 20 AFFINITY EG8150 40ELVALOY 1609 AC 82 LOTRYL 37EH175 30 LOTRYL 37EH550 30 LOTRYL 09 MG 0282.4 LOTRYL 15 MA 03 65.3 60 59 59 59 39 29 54 47 LOTRYL 24 MA 07 39LOTRYL 24MA005 42 LOTRYL 17BA07 65 69 LOTRYL 35 BA 320 45 KRATON G 16500 KRATON G 1652 0 6 KRATON G-1657 0 IRGANOX 1010-DD 0 1 1 1 1 1 1 1 1 1TIN FREE total 100 100 100 100 100 100 100 100 100 enthalpy of suitableformulas fusion of raw 1601- 1601- 1601- materials (J/g) 1601-88F1601-88G 1601-96E 1601-96F 1601-162A 1416-76J 1601-38D 56A 56B 73C 155PARAFFIN WAX 218.7 64 15 15 15 (65.5 deg C.) 138 PARAFFIN WAX 204.1(58-60 deg C.) 158 PARAFFIN WAX 211.7 30 40 30 25 25 15 (68-70 deg C.)PARAFLINT C80 226.7 16 25 25 15 POLYWAX 655, 239 24 24 24 PRILLEDESCOREZ 5320 0 WINGTACK EXTRA 0 ECR-188 0 EVA 18-150 60 EVATANE 28-06 35EPOLENE C-13 94 EPOLENE C-17 80 20 E82onMobil LD 202 80 20 AFFINITY PL1280 77.3 20 25 40 40 40 39 AFFINITY SM 1300 82.1 20 30 AFFINITY EG815040 ELVALOY 1609 AC 82 69 39 LOTRYL 37EH175 30 LOTRYL 37EH550 30 LOTRYL09 MG 02 82.4 LOTRYL 15 MA 03 65.3 43 34 15 LOTRYL 24 MA 07 39 LOTRYL24MA005 42 LOTRYL 17BA07 65 LOTRYL 35 BA 320 45 KRATON G 1650 0 35KRATON G 1652 0 10 15 KRATON G-1657 0 10 IRGANOX 1010-DD 0 1 1 1 1 1 1 11 1 TIN FREE total 100 100 100 100 100 100 100 100 100 100

TABLE 1b suitable formulas 1416-75B 1601-74C 1601-82B 1601-82C 1601-82D1601-84B 1601-84C 1601-86C 1601-86H Brookfield Viscosity of the 115000171000 107300 102000 119100 74800 82100 120500 65750 protector materialat 350 deg F. in mPa · s tensile test of the material elongation (%) 260440 430 379 505 275 445 493 509 std dev (%) 60 154 80 106 69 60 141 2513 enthalpy of fusion (calculation 129 110 126 123 133 130 135 121 131from raw materials' values) in J/g DSC enthalpy of fusion in J/g 127 109128 118 134 129 102 126 blocking tests at 70 deg C./6 none none nonenone none none none none none mils after 1 day migration at 60 deg C./6mils after 14 days on a 1-in2-wide contact area with HMPSA products highoil content adhesive staining middle middle low to low to middle middlelow middle low middle midddle tack none to none to none to none to noneto none to none to none to none to low low low low low low low low lowrosin ester containing adhesive staining low middle low low low low lowmiddle low tack none to none to none to none to none to none to none tonone to none to low low low low low low low low low suitable formulas1601- 1601-88F 1601-88G 1601-96E 1601-96F 1601-162A 1416-76J 1601-38D1601-56A 1601-56B 73C Brookfield Viscosity of the 170000 86100 9150078200 35450 48000 89870 108200 119200 155200 protector material at 350deg F. in mPa · s tensile test of the material elongation (%) 442 207564 600 686 678 220 350 410 617 std dev (%) 25 90 51 60 12 34 60 100 11077 enthalpy of fusion (calculation 120 132 127 131 139 141 138 137 137120 from raw materials' values) in J/g DSC enthalpy of fusion in J/g 109120 125 114 blocking tests at 70 deg C./6 none none none none none nonenone none none none mils after 1 day migration at 60 deg C./6 mils after14 days on a 1-in2-wide contact area with HMPSA products high oilcontent adhesive low low low low none to low none to none to none tonone to low low low low low none to none to none to none to none to noneto none to none to none none low low low low low low low low rosin estercontaining middle middle low low none to none to none to none to none tonone to adhesive low low low low low low none to none to none to none tonone none to none to none to none none low low low low low low low

TABLE 2a formulas unsuitable because of migration formulas unsuitablebecause elongation is not high enthalpy of resistance and DSC fusionspecific heat enough in tensile strength test fusion of raw 1601- 1601-1601- 1601- 1601- 1601- 1601- 1416- 1601- 1601- 1601- 1601- 1601- 1601-1601- materials 00A 00B 88A 88B 156C 156D 156B 75D 25A 25D 68E 84F 21D21E 21F 155 PARAFFIN WAX 218.7 10 15 15 13 12.3 15 16.0 (65.5 deg C.)138 PARAFFIN WAX 204.1 (58-60 deg C.) 158 PARAFFIN WAX 211.7 35 20 20 3940 33 20 15 (68-70 deg C.) PARAFLINT C80 226.7 10 10 20 15 POLYWAX 655,239 24 40 22 49.5 54 62.0 PRILLED KAYDOL USP 35 0 10 MINERAL OIL ESCOREZ5320 0 35 33 WINGTACK EXTRA 0 20 ECR-188 0 12 PICCOTEX 120 0 30 EVA18-150 60 33 EVATANE 28-06 35 39 EPOLENE C-13 94 39 EPOLENE C-17 80E82onMobil LD 202 80 AFFINITY PL 1280 77.3 AFFINITY SM 1300 82.1AFFINITY EG8150 40 ELVALOY 1609 AC 82 LOTRYL 37EH175 30 69 LOTRYL37EH550 30 69 LOTRYL 09 MG 02 82.4 60 44 52 LOTRYL 15 MA 03 65.3 30LOTRYL 24 MA 07 39 65 LOTRYL 24MA005 42 LOTRYL 17BA07 65 59 LOTRYL 35 BA320 45 VECTOR 4411 0 49 KRATON G 1650 0 21.0 KRATON G 1652 0 15 18.5 30KRATON G-1657 0 10 18.5 IRGANOX 1010-DD TIN 0 1 1 1 1 1 1 1 1 1 1 1 1.21 1 FREE total 100 100 100 100 100 100 100 100 100 100 100 100 100 100100

TABLE 2b formulas unsuitable because of migration resistance and DSCfusion specific heat capacity 1601- 1601- 1601- 1601- 1601- 1601- 1601-00A 00B 88A 88B 156C 156D 156B Brookfield Viscosity of the protector41000 64200 8640 2660 1490 8210 680 material at 350 deg F. in mPa · stensile test of the material elongation (%) 670 648 58 37 681 571 45 stddev (%) 60 31 16 7 10 84 10 enthalpy of fusion (calculation from 22 9985 85 84 98 90 raw materials' values) in J/g DSC enthalpy of fusion inJ/g 15 87 77 67 88 73 migration at 60 deg C./6 mils after 14 days on a1-in2-wide contact area with HMPSA products high oil content adhesivestaining stain to stain to stain to stain to stain to stain to stain tosupport support support support support support support tack high highhigh middle middle middle middle to high to high to high to high rosinester containing adhesive staining stain to stain to stain to stain tosupport support support support tack high high middle high to highformulas unsuitable because elongation is not high enough in tensilestrength test 1416- 1601- 1601- 1601- 1601- 1601- 1601- 1601- 75D 25A25D 68E 84F 21D 21E 21F Brookfield Viscosity of the protector 15100022400 92000 57200 30900 4360 4530 17000 material at 350 deg F. in mPa ·s tensile test of the material elongation (%) 34 15 32 41 51 34 4 5 stddev (%) 14 4 17 12 25 26 2 3 enthalpy of fusion (calculation from 140164 124 125 122 145 163 183 raw materials' values) in J/g DSC enthalpyof fusion in J/g 125 104 migration at 60 deg C./6 mils after 14 days ona 1-in2-wide contact area with HMPSA products high oil content adhesivelow low low to low middle low none to none to middle low low none tonone to low to none to none to low none to low low low middle low lowlow rosin ester containing adhesive low low low low middle none to noneto none to low low low none to none to none to none to none to none tonone none to low low low low low low low

TABLE 3a formulas unsuitable because of migration resistance and DSCfusion specific heat capacity suitable formulas enthalpy of fusion 1601-1601- Evatane Evatane 1601- 1601- 1601- 1601- 1601- of raw materials(J/g) 00A 00B 18-150 28-150 156B 110A 110D 110F 155E 155 PARAFFIN WAX(65.5 deg C.) 218.7 10 52 138 PARAFFIN WAX (58-60 deg C.) 204.1 49 40 48158 PARAFFIN WAX (68-70 deg C.) 211.7 35 33 PARAFLINT C80 226.7 10 10 10POLYWAX 655, PRILLED 239 KAYDOL USP 35 MINERAL OIL 0 10 ESCOREZ 5320 033 WINGTACK EXTRA 0 ECR-188 0 PICCOTEX 120 0 30 EVA 18-150 60 100 33 EVA28-150 33 100 EVATANE 28-06 35 EPOLENE C-13 94 EPOLENE C-17 80E82onMobil LD 202 80 AFFINITY PL 1280 77.3 AFFINITY SM 1300 82.1AFFINITY EG8150 40 20 ELVALOY 1609 AC 82 LOTRYL 37EH175 30 LOTRYL37EH550 30 LOTRYL 09 MG 02 82.4 LOTRYL 15 MA 03 65.3 35 17 LOTRYL 24 MA07 39 64 17 26 LOTRYL 24MA005 42 7 LOTRYL 17BA07 65 LOTRYL 35 BA 320 45VECTOR 4411 0 49 KRATON G 1650 0 KRATON G 1652 0 15 15 15 KRATON G-16570 10 IRGANOX 1010-DD TIN FREE 0 1 1 1 1 1 1 1 total 100 100 100 100 100100 100 100 100

TABLE 3b formulas unsuitable because of migration resistance and DSCfusion specific heat capacity suitable formulas Evatane Evatane 1601-1601- 1601- 1601- 1601- 1601-00A 1601-00B 18-150 28-150 156B 110A 110D110F 155E Brookfield Viscosity of the material at 41000 64200 not not680 33900 21900 4200 47180 350 deg F. in mPa · s measured measuredtensile test of the material elongation (%) 670 648 45 669 674 317 685standard deviation (%) 60 31 10 34 24 97 10 enthalpy of fusion(calculation from raw 22 98 60 33 90 124 122 131 147 materials' values)in J/g DSC enthalpy of fusion in J/g measured 15 87 60 33 73 105 117 109on actual DSC curves melting point observed on DSC curve 71 75 65 66(deg C.) melting area observed on DSC curve 15-85 25-90 20-90 25-85 (degC.) see DSC curve (FIG. 3) (FIG. 4) (FIG. 1) (FIG. 2) blocking tests at60 deg C./6 mils after 1 strong strong middle to strong middle to noneto none to none to none to day on a 1-in2-wide contact areas strongstrong low low low low obsevation of blocking forces migration at 50 degC./3 mils after 4 days on a 1-in2-wide contact area with HMPSA productshigh oil content adhesive staining high high high high middle to none tonone to none to none to high low low low low tack high high high highmiddle to none to none to none to none to high low low low low rosinester containing adhesive staining high high high high middle to none tonone to none to none to high low low low low tack middle to middle tomiddle to middle to middle to none none none none high high high highhigh

TABLE 4a H2543 H2543 H2543 H2543 H2543 H2543 skin material with no Armincontaminant 2-mils film 1601-00A 1416-75B % of skin material 0.0% 0.5%1.0% 2.0% 1.0% 2.0% dissolution visual observation when no change filmfloats to the top film floats to the top film floats to film floats tofilm floats to test putting the film after being after being the topafter the top after the top after submerged submerged being being beingsubmerged submerged submerged visual observation 30 min no change filmfloats to the top film floats to the top film is slightly film isslightly film is slightly after the film has been after being afterbeing melted melted melted incorporated submerged submerged visualobservation after no change film floats to the top film floats to thetop film appears to film is partially film is partlially turning 10times with a after being after being be be almost melted melted spatulasubmerged submerged completely melted visual observation after no changeLumps of different Lumps of different film appears film appears filmappears stirring at 50 rpm during size film present size film presentcompletely completely completely 30 min (or more) after 30 min. Lumpsafter 30 min. Lumps melted melted melted present after about 3 presentafter about 3 hours. hours.

TABLE 4b H2543 H2543 H2543 H2543 H2543 H2543 skin material with nocontaminant Armin 2-mils film 1601-00A 1416-75B % of skin material 0.0%0.5% 1.0% 2.0% 1.0% 2.0% aspect during the heat initial slightly cloudy,cloudy, water- cloudy, water- slightly cloudy, slightly cloudy, slightlycloudy, stability test water-white white white water-white water-whitewater-white after 24 hours light yellow, light yellow, dark brown lightyellow, light yellow, light yellow, slightly cloudy slightly cloudy skinalong slightly cloudy slightly cloudy slightly cloudy edges some brownstreaks after 48 hours slightly darker very slight brown slightly darkerslightly darker slightly darker in color brown streaking in color incolor in color streaking along edges and brown skin on top after 72hours slightly darker very slight some brown slightly darker slightlydarker slightly darker in color brown skinning, in color in color incolor streaking darker slightly darker in color softening point (R&B ininitial 157 158 161 162 158 160 deg F.) colour (Gardner) initial 1 1.51.5 1 1 1 after 72 hrs 3.5 5 6 5 5 5 viscosity in mPa · s at 300 initial2400 2457 2650 2330 2460 2510 deg F. after slightly mixing after 72 hrs670 525 750 400 650 690 by hand in the glass jar

TABLE 5 H2543 H2543 H2543 H2543 H2543 H2543 skin material with nocontaminant Armin 2-mils film 1601-00A 1416-75B % of skin material 0.0%0.5% 1.0% 2.0% 1.0% 2.0% 3 gsm: 3 non overlaping spirals; fresh peel:peel strength in 181 206 194 203 197 2″ & ¼ wide spray g/in 24 hrs aftercoating 1st substrate = standard PE standard deviation 21 25 26 15 172nd substrate = standard NW Failure Mode Cohesive Cohesive CohesiveCohesive Cohesive line speed = 560 feet/min Failure Failure FailureFailure Failure (OT = 0.25 s) peel strength in g/in when 159 133 138 140143 laminates have spent 4 weeks at 130 deg F. standard deviation 37 2720 37 19

TABLE 6 H2994 H2994 H2994 H2994 H2994 H2994 skin material no contaminant82B 75B 96F Coating Weight of adhesive: % of skin material 15 g/m² 0.0%1.0% 2.0% 1.0% 2.0% 1.0% Initial creep resistance 72% 72% 76% 68% 77%72% standard deviation 5% 4% 5% 3% 2% 5% after ageing 4 weeks at room57% 57% 56% 62% 57% 59% temperature standard deviation 5% 4% 5% 4% 5% 4%after ageing 4 weeks at 130 54% 52% 55% 59% 55% 61% deg F. standarddeviation 6% 7% 5% 5% 6% 5% Initial creep resistance 80% 80% 79% 79% 77%75% standard deviation 3% 4% 4% 4% 4% 5% after ageing 4 weeks at room70% 73% 75% 66% 70% 71% temperature standard deviation 3% 5% 6% 3% 5% 5%after ageing 4 weeks at 130 68% 72% 73% 71% 69% 71% deg F. standarddeviation 4% 5% 7% 4% 5% 8%

TABLE 7 H2548 no H2548 H2548 skin material contaminant 1601-155E1601-110F % of skin material 0.0% 2.0% 1.0% 180 degree T-Peel 2231.02206.5 2104.9 maximum of the peel value (g/in) standard deviation 104.3193.1 122.9 180 degree T-Peel 2006.8 2066.1 2132.3 average peel forcevalue over displacement (g/in) standard deviation 60.6 138.4 73.9softening point in deg F. 196.4 196.8 197.1 looptack 2514.20 2057.802199.4 (maximum load in lbf) standard deviation 210.70 140.60 271.8viscosity at 325 deg F. in 6337.5 5937.5 5725 mPa · s SAFT value in degF. 137.3 139.7 138.7 standard deviation 2.1 0.6 2.1

1. A package, comprising: a plastic mass having a finite size and shape;and a polymeric film surrounding said plastic mass, said polymeric filmhaving a composition comprising: at least about 25% by weight of a waxmaterial; and wherein the film composition has an enthalpy of fusion ofat least about 100 J/g and an elongation value at break of at leastabout 100%.
 2. The package of claim 1 wherein said polymeric film has athickness of 10 microns to 100 microns.
 3. The package of claim 1wherein said polymeric film has a thickness of 10 microns to 300microns.
 4. The package of claim 1 wherein said polymeric film has athickness of 40 microns to 2000 microns.
 5. The package of claim 1wherein said wax material comprises at least 40% by weight of said filmcomposition.
 6. The package of claim 1 wherein said wax materialcomprises 25% to 65% by weight of said film composition.
 7. The packageof claim 1 wherein said plastic mass is a material selected from thegroup consisting of a thermoplastic composition, a thermoplasticcompound, a thermoplastic polymer, a thermosetting composition, athermosetting compound, a thermosetting polymer, a hot melt composition,a hot melt compound, a hot melt polymer, a hot melt adhesivecomposition, a hot melt adhesive compound, a hot melt adhesive polymer,and blends thereof.
 8. The package of claim 1 wherein said plastic masscomprises a hot melt adhesive composition.
 9. The package of claim 1wherein said wax material is selected from the group consisting of apetroleum wax, a synthetic wax, a polyolefin wax, an animal wax, avegetable wax, and mixtures thereof.
 10. The package of claim 9 whereinsaid petroleum wax is a paraffin wax.
 11. The package of claim 9,wherein said synthetic wax is a Fischer-Tropsch wax.
 12. The package ofclaim 9 wherein said polyolefin wax is selected from the groupconsisting of polyethylene, polypropylene, ethylene-based copolymers,propylene-based copolymers and mixtures thereof.
 13. The package ofclaim 1 wherein said polymeric film composition further comprises: about5% to about 65% by weight of a partially crystalline ethylene-basedpolymer comprising a homopolymer, a copolymer, a terpolymer or aninterpolymer having a melt flow index of 0.05 g/10 min. to 800 g/10 min.at 190° C. and a DSC melting point of 40° C. to 130° C.; about 0% toabout 40% by weight of a thermoplastic elastomeric block copolymerhaving a structure A-B, A-B-A, A-(B-A)_(n)-B, or (A-B_()n)-Y wherein Acomprises a polyvinyl aromatic block having a Tg higher than 80° C., Bcomprises a rubbery midblock having a Tg lower than −10° C., Y comprisesa multivalent compound, and n is an integer of at least 3; about 0% toabout 25% by weight of an elastomer comprising a copolymer or terpolymerhaving a Tg lower than −10° C., said elastomer selected from the groupconsisting of an ethylene-based elastomer, a propylene-based elastomer,and blends of ethylene-based and propylene-based elastomers; and whereinthe amount of partially crystalline ethylene-based polymer,thermoplastic elastomeric block copolymer, and elastomer comprises about30% or more of the total film composition.
 14. The package of claim 13wherein said ethylene-based polymer is selected from the groupconsisting of LDPE, VLDPE, LLDPE, MDPE, HDPE, EVA, EAA, EMA, EBA, EE2HA,EO, EP, EB EH, ESI and blends thereof.
 15. The package of claim 13wherein said ethylene-based based polymer is EMA.
 16. The package ofclaim 13 wherein said ethylene-based polymer is EO.
 17. The package ofclaim 13 wherein said ethylene-based polymer is EB.
 18. The package ofclaim 13 wherein said ethylene-based polymer has a melt flow index below30 g/10 min.
 19. The package of claim 13 wherein said ethylene-basedpolymer has a melt flow index below 7 g/10 min.
 20. The package of claim13 wherein said ethylene-based based polymer has a DSC melting pointbelow 100° C.
 21. The package of claim 13 wherein said block copolymeris selected from the group consisting of SB, SBS, SIS, SIBS, SEBS, SEP,SEPS, SBBS and blends thereof.
 22. The package of claim 13 wherein saidblock copolymer is SEBS.
 23. The package of claim 13 wherein said blockcopolymer has a melt flow index below 15 g/10 min. at 190° C.
 24. Thepackage of claim 13 herein said block copolymer comprises 15% or less ofsaid film composition.
 25. The package of claim 13 wherein saidelastomer is selected from the group consisting of EPR, EPDM and blendsthereof.
 26. The package of claim 13 wherein said elastomer is EPRhaving a propylene content of about 15% to 70% by weight.
 27. Thepackage of claim 13 wherein said elastomer is EPR having a propylenecontent of about 20% to 45% by weight.
 28. The package of claim 13wherein said elastomer is EPDM having an ethylene content of from about20% to 80% by weight, a propylene content of from about 15% to 70% byweight, and a diene content of about 2% to 15% by weight.
 29. Thepackage of claim 13 wherein said elastomer comprises 15% or less of saidfilm composition.